Cornerstone Institute Contact Details By Zwadmissions | August 24, 2022 0 Comment Cornerstone Institute Contact Details Contact Details Telephone: +27 (0)21 448 0050 Physical Address: Cornerstone Institute, 1 Cedar Street, Sandown, Milnerton Rural, Western Cape, South Africa, 7441 Postal Address: P. O. Box 13434, Observatory, 7935, Western Cape